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Browse Prior Art Database

Bistable Heterojunction Structure

IP.com Disclosure Number: IPCOM000048471D
Original Publication Date: 1982-Feb-01
Included in the Prior Art Database: 2005-Feb-08
Document File: 2 page(s) / 37K

Publishing Venue

IBM

Related People

Dumke, WP: AUTHOR [+3]

Abstract

In a modulation-doped heterostructure as shown in Fig. 1, when electron are heated by a voltage applied along the central layer, they will transfer into the doped GaAlAs and will experience increased scattering so that a negative differential resistance with charge transfer in real space rather than momentum space occurs. The presence of traps in the GaAlAs produces hysteresis so that in principle a memory is constructed by introducing deep traps into the GaAlAs.

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Bistable Heterojunction Structure

In a modulation-doped heterostructure as shown in Fig. 1, when electron are heated by a voltage applied along the central layer, they will transfer into the doped GaAlAs and will experience increased scattering so that a negative differential resistance with charge transfer in real space rather than momentum space occurs. The presence of traps in the GaAlAs produces hysteresis so that in principle a memory is constructed by introducing deep traps into the GaAlAs.

An improved structure employs layers of Ga(x)Al(1x)As arranged to vary the conduction band as shown in Fig. 2. In this structure, only the GaAs is doped (n- type). If contacts are made to the GaAs regions so as to have current along it perpendicular to the plane of Fig. 2, then when the electrons are heated sufficiently, they will transfer into well 2 until a sufficient potential is built up to balance off the thermionic emission over the barrier or thermally induced tunneling through it. The potential will then be as shown in Fig. 3. The static I-V characteristics would look like those in Fig. 4. As long as the Boltzmann energy (kT) much less than E(1) and the intermediate GaAlAs layer is thick enough to prevent tunneling, the electrons cannot transfer back, which gives rise to the hysteresis.

In an erasable read-only memory EROM the memory is cleared by heating or exposure to IR light with a photon energy h upsilon much greater than E(1) but preferably less than E(2)....